Hobbies And Interests
Color
Robin's-egg blue or sky-blue turquoises, with no veining, are considered the finest colored stones. Sky-blue stones are often described as Persian blue, even though they can be found in other areas of the world, because stones of this color were traditionally mined in Iran, which was once known as Persia. A naturally occurring perfect blue stone that turns green when heated can still only be found today in one mine in Neyshabur, Iran.
Value
The value of a turquoise stone is affected by the evenness of its color, more than the color itself, although blue stones tend to be more valuable than green ones. Other factors that affect value include the hardness of the stone, its ability to be polished without having to be enhanced or stabilized, and the pattern of any veining that exists on it. Stones with an even, interconnected spiderweb pattern are the most valued.
Enhancements/Treatments
Most turquoise is treated in one way or another so it will take a polish better. Even high-grade natural stones may be given a surface coat of paraffin wax. Softer stones can have waxes or oils pressed into them to make them harder. Enhanced turquoise has vaporized quartz added to it to make the stone harder so it will polish well. Since quartz naturally occurs with some turquoise, it can be difficult to tell if a stone's been enhanced. Plastic resin is used to fill microscopic gaps in lower-grade turquoise so it can be used to make jewelry. This kind of turquoise is called stabilized or treated turquoise. Turquoise from China is usually treated with wax to deepen and stabilize the color. Reconstituted turquoise is made by combining crushed turquoise scraps with plastic binder and blue dye. Block turquoise is manmade and doesn't contain any turquoise stone at all.
Location
Turquoise is found in arid and semiarid regions like those that occur in the southwest desert of the U.S. It forms as a secondary mineral in volcanic rocks located near copper deposits, when chemicals that leach out of rock formations are replaced with copper, phosphates and other chemicals. Turquoise deposits are found in many places around the world, including Africa, Australia, China, Iran, Mexico, Russia, Siberia and the U.S.
Care
Turquoise is susceptible to being scratched or damaged by sharp blows, hot water and chemicals. The pores in the stone also absorb body oils that cause it to yellow over time. Don't use chlorine, steam or ultrasonic cleaners on turquoise. Wash in mild, lukewarm soapy water and wipe with a damp cloth after wearing.